Forward link power control of multiple data streams transmitted to a mobile station using a common power control channel

ABSTRACT

A method and apparatus for controlling transmit power levels of a plurality of different data streams transmitted from at least one base station to a mobile station in a mobile radio communication system is described. A stream of power control commands is formed at the mobile station in accordance with either the first or second received data stream. A power control signal is formed at the mobile station from the first stream of power control commands and transmitted to the base station.

CLAIM OF PRIORITY UNDER 35 U.S.C. §120

[0001] The present Application for Patent is a Divisional and claimspriority to patent application Ser. No. 09/824,860 entitled “ForwardLink Power Control of Multiple Data Streams Transmitted to a MobileStation Using a Common Power Control Channel” filed Apr. 2, 2001, whichis assigned to the assignee hereof and hereby expressly incorporated byreference herein.

BACKGROUND

[0002] I. Field

[0003] This invention relates to the field of communications systemsand, in particular, to a method for controlling the transmission powerlevel of multiple data streams sent from one or several base stations toa mobile station in a mobile radio telecommunication system.

[0004] II. Prior Art

[0005] In a mobile telephone communication system, one or several basestations transmit information, such as voice information, or data, orboth to a mobile station. Each base station supports one or severalsectors. For example in EIA/TIA-95-A CDMA systems it is common that eachbase station supports three individual sectors, with each sectortransmitting different information. Voice and data transmissions from abase station to one or more mobile stations typically occur on a forwardlink traffic channel. A mobile station receives the information from theforward link traffic channel, decodes the information, and determines aframe error rate associated with the decoded information. The frameerror rate of the decoded information can be adversely affected by, forexample, fading conditions in the forward link channel. Furthermore atraffic channel can be transmitted from several base stations or severalsectors of the same base station. The mobile station will then combinethe signals from the different sectors for improved decoding, in aprocess that is often referred to in the prior art as soft-handoff. Theset of base station sectors transmitting the same data signal is usuallynamed an “active set”. It will be understood by those skilled by the artthat the term soft handoff refers to soft handoff between different basestations as well as soft handoff between different sectors of the samebase station.

[0006] In some mobile radio communication systems such as, for example,mobile radio systems that use code division multiple access (CDMA)modulation, the frame error rate at the mobile station is used tocontrol the transmit power level sent to the mobile on the forward linktraffic signal. For example, in such systems a desired ratio of signalto noise powers is derived from the desired frame error rate. Anestimate of the actual signal to noise ratio received by the mobile isthen used to generate a stream of power control commands that is sentfrom the mobile station back to the base stations in the active set.Each power control command in the stream causes the base station toeither increase (by, for example, 1 dB), decrease (by, for example, 1dB) or hold constant the transmit power sent to the mobile station onthe forward link traffic channel.

[0007] Using such a power control system allows the mobile station tocause the base station to increase the transmit power to compensate forconditions such as a fade. Likewise, the power control system permitsthe base station to save power when the channel conditions are morefavorable and a predetermined error rate can be maintained using a lowertransmit power.

[0008] In modern mobile telephone communication systems, several datastreams (e.g., fax transmissions, internet transmissions, voice callsetc.) can be transmitted to a mobile station concurrently. In systemssuch as CDMA systems, the transmission of such data streams can occur onthe same forward link traffic channel (i.e., frequency channel). In suchcases, each data stream (e.g., voice, fax, internet, etc.) transmittedfrom a particular base station to the mobile station on a given forwardlink is modulated using a different spreading code often called a Walshcode that permits each data stream to be separately demodulated at themobile station. Different base stations can transmit on the forward linkwith the same spreading code when they utilize a different scramblingcode (often called PN code).

[0009] Where multiple data streams are transmitted from a one or severalbase stations to a mobile station on one or several forward links, thetransmit power level of each of the data streams should be controlled asdescribed above. However, sending a separate stream of power controlcommands on the reverse link from the mobile station back to each basestation in order to control the transmit power of each data streamresults in a substantial increase in system overhead.

[0010] Thus, it would be desirable to provide a system for forward linkpower control that minimized the overhead required to send power controlcommands from the mobile station back to a base station in cases wherethe base station is transmitting multiple data streams to the mobilestation.

SUMMARY

[0011] The present invention is directed to a method and apparatus forcontrolling transmit power levels of a first data stream transmittedfrom each base station in a first active set of base stations to amobile station in a mobile radio communication system, and forcontrolling transmit power levels of a second data stream transmittedfrom each base station in a second active set of base stations to themobile station.

[0012] In a first embodiment, a stream of power control commands isformed at the mobile station for each base station in either the firstor second active set in accordance with either the first and/or secondreceived data stream from each such base station. A power control signalis formed at the mobile station by interleaving the streams of powercontrol commands, and the interleaved stream of power control commandsis then transmitted to the base stations in the first and second activeset. A received stream of power control commands is formed bydeinterleaving the received power control signal at a given base stationin the first and second active sets, and the transmit power levels ofthe first and second data streams from the given base station are bothcontrolled in accordance with the received stream of power controlcommands. Thus, in this embodiment, a single stream of power controlcommands is used to control the transmit power levels of multipledifferent data streams (e.g., a voice data stream and a fax data stream)transmitted to a mobile station from a common base station.

[0013] In accordance with a further aspect of the embodiment set forthabove, the second active set of base stations may be a subset of thefirst active set of base stations. In this case, the power controlstream for each base station that is in the first active set but not inthe second active set will be formed only in accordance with the firstdata stream from such base station.

[0014] In accordance with a still further embodiment, the presentinvention uses a single interleaved power control signal to transmitmultiple power control command streams to each base station in both thefirst and second active sets, wherein each of the power control commandstreams is used to control the transmit power of a different data streamsent from each base station to the mobile station. In this embodiment,first and second data streams are transmitted from each base station inthe first and second active sets and received at the mobile station. Astream of power control commands is formed at the mobile station inaccordance with the first received data stream from each base station inthe first active set, and a stream of power control commands is formedat mobile station in accordance with the second received data streamfrom each base station in the second active set. A power control signalis next formed at the mobile station by interleaving the streams ofpower control commands, and the interleaved power control signal istransmitted from the mobile station to each base station in the firstand second active sets. First and second received streams of powercontrol commands are formed at a given base station in the first andsecond active sets by deinterleaving the received power control signalat the given base station. The transmit power level of the first datastream is then controlled from the given base station in accordance withthe first received stream of power control commands, and the transmitpower level of the second data stream is controlled from the given basestation in accordance with the second received stream of power controlcommands.

[0015] In accordance with a further aspect of the embodiment set forthabove, the second active set of base stations may be a subset of thefirst active set of base stations. In this case, the power controlstream for each base station that is in the first active set but not inthe second active set will be formed only in accordance with the firstdata stream from such base station.

[0016] In accordance with a still further aspect, the signal strengthmeasurements of two corresponding data streams transmitted to a mobilestation from first and second base stations are examined in order todetermine the power control commands used for controlling the transmitpower of one (or both) of the two corresponding data streams transmittedfrom the two base stations. This aspect of the invention thus usesinformation about the signal strength of a data stream transmitted to amobile station from a first base station for generating power controlcommands used for controlling the transmit power of a corresponding datastream transmitted to the mobile station from a second (different) basestation. A first data stream is transmitted from first and second basestations to the mobile station, and a second data stream is transmittedfrom the first base station to the mobile station. In this embodiment,the transmit power level of the first data stream from the first basestation is then controlled at the mobile station by monitoring thesignal quality of the first data stream received from the first basestation as well as the signal quality of the first data stream receivedfrom the second base station. Similarly, the transmit power level of thefirst data stream from the second base station is controlled at themobile station by monitoring the signal quality of the first data streamreceived from the second base station as well as the signal quality ofthe first data stream received from the first base station.

[0017] In accordance with yet a still further aspect, the signalstrength measurements of two corresponding data streams transmitted to amobile station from first and second base stations are examined in orderto determine the power control commands used for controlling thetransmit power of one (or both) of the two corresponding data streamstransmitted from the two base stations. This aspect of the inventionthus also uses information about the signal strength of a data streamtransmitted to a mobile station from a first base station for generatingpower control commands used for controlling the transmit power of acorresponding data stream transmitted to the mobile station from asecond (different) base station. A first data stream is transmitted fromfirst and second base stations to the mobile station, and a second datastream is transmitted from the first base station to the mobile station.In this embodiment, the transmit power level of the first data streamfrom the second base station is then controlled at the mobile station bymonitoring the signal quality of the first data stream received from thefirst base station as well as the signal quality of the first datastream received from the second base station. The transmit power levelsof the first and second data streams from the first base station arecontrolled at the mobile station by monitoring the signal quality of thesecond data stream received from the first base station.

[0018] The aspects of the invention discussed in the two paragraphsimmediately above can be generalized such that the system uses differentsignal strengths from corresponding data streams transmitted to a mobilestation from a first active set of base stations for generating powercontrol commands used for controlling the transmit power of thecorresponding data streams transmitted to the mobile station from eachbase station in the first active set. In this more general embodiment,the first data stream is transmitted from base stations in the firstactive set to the mobile station, and a second data stream istransmitted from base station(s) in a second active set of one or morebase stations to the mobile station. A first set of power controlcommand streams is then formed at the mobile station and transmitted tothe base stations in the first active set, wherein each stream of powercontrol commands in the set is determined in accordance with the firstdata streams received from all base stations in the first active set ofbase stations. The first and second base stations discussed in the twoparagraphs immediately above would be included in the first active setof base stations, the second base station would be included in thesecond active set of base stations, and the second active set of basestations may or may not be a subset of the first active set of basestations.

[0019] In a further alternate embodiment, the first stream of powercontrol commands is formed at the mobile station in accordance with thefirst and second data streams received at the mobile station only fromthe base stations in the second active set. The second stream of powercontrol commands is formed at the mobile station in accordance with thefirst data streams or second data streams or both data streams receivedat the mobile station from the base stations in the first active set butnot in the second active set. The mobile station then forms aninterleaved power control signal by interleaving the first and secondstreams of power control commands, and the interleaved power controlsignal is transmitted from the mobile station on the reverse link. Theinterleaved power control signal is received at both the base stationsin the first and second active sets. The base stations form a firstreceived stream of power control commands by deinterleaving the receivedinterleaved power control signal, and a second received stream of powercontrol commands by deinterleaving the received interleaved powercontrol signal. The transmit power level of the first and second datastreams transmitted by the base stations in the second active set isthen controlled in accordance with the first received stream of powercontrol commands, and the transmit power level of the first data streamtransmitted by the base stations in the first active set but not in thesecond active set is controlled in accordance with the second receivedstream of power control commands.

[0020] In accordance with a still further embodiment where thecommunication system includes first and second active sets, the firstdata stream is transmitted from the base stations in the first activeset to the mobile station, and the second data stream is transmittedfrom the base stations in the second active set to the mobile station.In this embodiment, the second active set is a subset of the firstactive set. A first stream of power control commands is formed at themobile station in accordance with the first data stream received at themobile station from the base stations in the first active set. A secondstream of power control commands is formed at the mobile station inaccordance with the first data stream or second data stream or both datastreams received at the mobile station from the base stations in thesecond active set. The mobile station then forms an interleaved powercontrol signal by interleaving the first and second streams of powercontrol commands, and the interleaved power control signal istransmitted from the mobile station to all the base stations in bothactive sets. The interleaved power control signal is received at basestations in both the first and second active sets. The base stationsform a first received stream of power control commands byde-interleaving the received interleaved power control signal, and asecond received stream of power control commands by de-interleaving thereceived interleaved power control signal. The transmit power level ofthe first and second data streams transmitted by the base stations thatare in the second active set is controlled by using the commands of thefirst or a combination of both streams of power control commands. Thetransmit power level of the first data stream transmitted by the basestations that are in the first active set but not in the second activeset is controlled in accordance with the first received stream of powercontrol commands or a combination of the first and second receivedstreams of power control commands.

[0021] This previous embodiment is particularly useful when the secondstream of data is intermittent and only transmitted from a subset of thebase stations in the first active set.

[0022] In a further embodiment where the radio telephone communicationsystem includes different first and second active sets, the first datastream is transmitted from the base stations in the first active set tothe mobile station and the second data stream is transmitted from thebase stations in the second active set to the mobile station. A singlestream of power control commands is then formed at the mobile station inaccordance with the first data stream received from the base stations inthe first active set. The mobile station then forms a power controlsignal with the power control commands, and the power control signal istransmitted from the mobile station to all the base stations in bothactive sets. The power control signal is received at base stations inboth the first and second active sets. The base stations in the firstactive set and the base stations in the second active set form areceived stream of power control commands by decoding the received powercontrol signal. The transmit power level of the first data streamtransmitted by the base stations in the first active set and thetransmit power level of the second data stream transmitted by the basestations in the second active set is then controlled in accordance withthe received stream of power control commands. The difference intransmitted power between the first and second data stream is adjustedby means of a separate mechanism. For example a message sent time totime from the mobile station to the base stations or an outer loop basedon the QoS (Quality of Service) currently measured and the desired QoSof the second data stream after decoding by the mobile station. This QoScould be a frame error rate or other.

[0023] In an alternate embodiment of the previous embodiment, the powercontrol commands are generated based on both the first and second datastreams received at the mobile station.

[0024] In the above embodiments, the mobile station preferably formseach stream of power control commands by monitoring either a frame errorrate or a signal-to-noise ratio associated with a given received datastream. Furthermore, the first and second streams of power controlcommands are preferably generated in accordance with an interleavingpattern, and the commands from each stream are only generated andinserted when required by the interleaving pattern. This ensures that noexcess commands are generated whose transmission would delay newercommands. This also ensures that the interleaving process will not delayunnecessarily the power control commands from one stream or another.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The features, objects, and advantages of the present inventionwill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings in which like referencecharacters identify corresponding elements throughout and wherein:

[0026]FIG. 1A shows a mobile radio station that generates an interleavedpower control signal for controlling the transmit power levels of aplurality of different data streams transmitted to the mobile stationfrom one or more base stations, in accordance with a preferredembodiment of the present invention. In the embodiment of FIG. 1A, thetransmit power levels of different data streams transmitted to themobile station from the same base station are controlled using a commonstream of power control commands included in the interleaved powercontrol signal.

[0027]FIG. 1B shows an alternate preferred embodiment of the mobileradio station of FIG. 1A. In FIG. 1B, the mobile radio station receivesa plurality of different data streams from at least one base station,and only a single data stream from at least one base station.

[0028]FIG. 1C shows a mobile radio station that generates an interleavedpower control signal for controlling the transmit power levels of aplurality of different data streams transmitted to the mobile stationfrom one or more base stations, in accordance with an alternatepreferred embodiment of the present invention. In the embodiment of FIG.1C, the transmit power levels of different data streams transmitted tothe mobile station from the same base station are controlled usingdifferent streams of power control commands included in the interleavedpower control signal.

[0029]FIG. 1D shows an alternate preferred embodiment of the mobileradio station of FIG. 1C. In FIG. 1D, the mobile radio station receivesa plurality of different data streams from at least one base station,and only a single data stream from at least one base station.

[0030]FIG. 1E shows an alternate embodiment of the mobile radio stationof the present invention. In this embodiment, a first data stream istransmitted to the mobile station from at least first and second basestations. The transmit power level of the first data stream from thefirst base station is then controlled at the mobile station bymonitoring the signal quality of the first data stream received from thefirst base station as well as the signal quality of the first datastream received from the second base station. Similarly, the transmitpower level of the first data stream from the second base station iscontrolled at the mobile station by monitoring the signal quality of thefirst data stream received from the second base station as well as thesignal quality of the first data stream received from the first basestation.

[0031]FIG. 1F shows a further alternate embodiment of the mobile radiostation of the present invention. In this embodiment, a first datastream is transmitted to the mobile station from at least first andsecond base stations, and a second data stream is transmitted to themobile station from the first base station. The transmit power level ofthe first data stream from the second base station is controlled at themobile station by monitoring the signal quality of the first data streamreceived from the first base station as well as the signal quality ofthe first data stream received from the second base station. Thetransmit power levels of the first and second data streams from thefirst base station are controlled at the mobile station by monitoringthe signal quality of the second data stream received from the firstbase station.

[0032]FIG. 1G shows a further alternate embodiment of the mobile radiostation of the present invention. In this embodiment, a first (common)power control command stream is generated from the first data streamfrom each base station in the second active set and the second datastream from each base station in the second active set, and then usedfor controlling the transmit power level of the second data stream fromeach base station in the second active set and the first data streamfrom each base station in the second active set. A second (common) powercontrol stream is generated from the first data stream from each basestation in the first active set and not in the second active set, andthen used for controlling the transmit power level of the first datastream from each base station in the first active set and not in thesecond active set.

[0033]FIG. 1H shows a further alternate embodiment of the mobile radiostation of the present invention. In this embodiment, a coarse powercontrol command stream is generated from the first data stream from eachbase station in the first active set, and then used for controlling thetransmit power level of the first data stream from each base station inthe first active set and the transmit power level of the second datastream from each base station in the second active set. A fine powercontrol stream is generated from the first data stream from each basestation in the second active set and the second data stream from eachbase station in the second active set, and then used in combination withthe coarse power control command stream for controlling the transmitpower level of the second data stream from each base station in thesecond active set and the first data stream from each base station inthe second active set.

[0034]FIG. 1I shows a further alternate embodiment of the mobile radiostation of the present invention. In this embodiment, a coarse powercontrol command stream is generated from the first data stream from eachbase station in the first active set and the second data stream fromeach base station in the second active set, and then used forcontrolling the transmit power level of the first data stream from eachbase station in the first active set and the transmit power level of thesecond data stream from each base station in the second active set. Afine power control stream is also generated and used in combination withthe coarse power control command stream for adjusting the transmit powerlevel of the second data stream from each base station in the secondactive set that is also in the first active set.

[0035]FIG. 2A shows a base station that receives a plurality ofinterleaved power control signals from a plurality of mobile stations,and uses the power control signals to control the transmit power levelsof different data streams transmitted to the mobile stations, inaccordance with a preferred embodiment of the present invention. In theembodiment of FIG. 2A, the transmit power levels of different datastreams transmitted to the same mobile station from the base station arecontrolled using a common stream of power control commands included inan interleaved power control signal.

[0036]FIG. 2B shows an alternate preferred embodiment of the basestation of FIG. 2A. In FIG. 2B, the base station transmits a pluralityof different data streams to at least one mobile station, and only asingle data stream to other mobile stations on the base station'sforward link.

[0037]FIG. 2C shows a base station that receives a plurality ofinterleaved power control signals from a plurality of mobile stations,and uses the power control signals to control the transmit power levelsof different data streams transmitted to the mobile stations, inaccordance with an alternate preferred embodiment of the presentinvention. In the embodiment of FIG. 2C, the transmit power levels ofdifferent data streams transmitted to the same mobile station from thebase station are controlled using different streams of power controlcommands included in an interleaved power control signal.

[0038]FIG. 2D shows an alternate preferred embodiment of the basestation of FIG. 2C. In FIG. 2D, the base station transmits a pluralityof different data streams to at least one mobile station, and only asingle data stream to other mobile stations on the base station'sforward link.

[0039]FIG. 2E shows a base station that receives a plurality of powercontrol signals formed from a plurality of mobile stations of the formshown in FIG. 1F, and uses the power control signals to control thetransmit power levels of first and second data streams transmitted tothe mobile stations. In the embodiment of FIG. 2E, the base station isin both active sets of the two mobile stations shown as being servicedby the base station.

[0040]FIG. 2F shows a base station that receives a plurality of powercontrol signals formed from a plurality of mobile stations of the formshown in FIG. 1F, and uses the power control signals to control thetransmit power levels of first and second data streams transmitted tothe mobile stations. In the embodiment of FIG. 2F, the base station isin the first active set and not the second active set of the two mobilestations shown as being serviced by the base station.

[0041]FIG. 2G shows a base station that receives a plurality of powercontrol signals formed from a plurality of mobile stations of the formshown in FIG. 1G, and uses the power control signals to control thetransmit power levels of first and second data streams transmitted tothe mobile stations. In the embodiment of FIG. 2G, the base station isin both active sets of the two mobile stations shown as being servicedby the base station.

[0042]FIG. 2H shows a base station that receives a plurality of powercontrol signals formed from a plurality of mobile stations of the formshown in FIG. 1G, and uses the power control signals to control thetransmit power levels of first data streams transmitted to the mobilestations. In the embodiment of FIG. 2H, the base station is in the firstactive set and not the second active set of the two mobile stationsshown as being serviced by the base station.

[0043]FIG. 2I shows a base station that receives coarse and fine powercontrol signals formed from a plurality of mobile stations of the formshown in FIG. 1H, and uses the power control signals to control thetransmit power levels of first and second data streams transmitted tothe mobile stations. In the embodiment of FIG. 2I, the base station isin both active sets of the two mobile stations shown as being servicedby the base station.

[0044]FIG. 2J shows a base station that receives coarse power controlsignals formed from a plurality of mobile stations of the form shown inFIG. 1H, and uses the power control signals to control the transmitpower levels of first data streams transmitted to the mobile stations.In the embodiment of FIG. 2H, the base station is in the first activeset and not the second active set of the two mobile stations shown asbeing serviced by the base station.

[0045]FIG. 2K shows a base station that receives coarse and fine powercontrol signals formed from a plurality of mobile stations of the formshown in FIG. 1I, and uses the power control signals to control thetransmit power levels of first and second data streams transmitted tothe mobile stations. In the embodiment of FIG. 2K, the base station isin both active sets of the two mobile stations shown as being servicedby the base station.

[0046]FIG. 2L shows a base station that receives coarse power controlsignals formed from a plurality of mobile stations of the form shown inFIG. 1I, and uses the power control signals to control the transmitpower levels of first data streams transmitted to the mobile stations.In the embodiment of FIG. 2L, the base station is in the second activeset and not the first active set of the two mobile stations shown asbeing serviced by the base station.

DETAILED DESCRIPTION OF THE INVENTION

[0047]FIG. 1A shows a mobile radio station 100 a that generates aninterleaved power control bit stream 110 for controlling the transmitpower levels of a plurality of different data streams 120, 120 a, 122,122 a, 124, 124 a that are transmitted to the mobile radio station fromone or more base stations. Data streams 120, 122, . . . 124, carry thesame information (e.g., the same voice transmission) and are transmittedfrom a first active set of base stations (i.e., BS1, BS2, . . . BSn).Data streams 120 a, 122 a, . . . 124 a, carry the same information(e.g., the same internet or fax transmission) and are simultaneouslytransmitted from a second active set of base stations (i.e., BS1, BS2,BSn). As explained more fully below in connection with variousalternative embodiments, the second active set of base stations may ormay not be a subset of the first active set. Data streams 120, 120 a,122, 122 a, 124, 124 a are transmitted to the mobile radio station on,for example, a common frequency band using code division multiple access(CDMA) or time division multiple access (TDMA) modulation. Multiple datastreams from different base stations are used to transmit multiplerepresentations of the same information to the mobile radio stationwhen, for example, the mobile radio station is in a soft handoff betweentwo or more base stations or in cases where diversity signals are usedto achieve better reception at the mobile station. The transmission ofmultiple versions of the same data signal to a given mobile station fromdifferent base stations to perform a soft handoff or to achieve transmitdiversity is well known in the art.

[0048] In mobile station 10 a, the data streams 120, 120 a received fromBS1 are provided to a power control command generator 130 whichgenerates a single stream of power control commands from the receiveddata streams. In the embodiment of FIG. 1A, power control commandgenerator 130 optionally selects either data stream 120 or data stream120 a (or a combination thereof) to monitor. Thereafter, the powercontrol command generator 130 monitors either the receivedsignal-to-noise ratio or the frame error rate associated with theselected data stream (or the sum of the received signal-to-noise ratioor the frame error rate associated with both data streams 120, 120 a ifthe combination is being monitored), and generates a series of forwardlink power control commands 140 based on this information. Each powercontrol command in stream 140 will, for example, represent a command toBS1 indicating that BS1 should either increase or decrease the transmitpower level used to transmit subsequent frames of data streams 120, 120a to mobile radio station 100 a. Deriving such a stream of power controlcommands using either the received signal-to-noise ratio or the frameerror rate of a single received signal is well known in the art. Where acombination of data streams 120, 120 a is being monitored, the sum ofthe received signal-to-noise ratios associated with each data stream ispreferably compared to a threshold representing a desired sum ofsignal-to-noise ratios expected from the combination of data streams120, 120 a in order to generate the stream of power control commands. Inthe embodiment of FIG. 1A, a single, common stream of power controlcommands 140 is thus generated for both data streams 120, 120 a usingeither one of the two data streams or both streams. This aspect of theinvention recognizes that when multiple data streams are transmitted ona forward link traffic channel from a base station to a given mobilestation, fading conditions in the traffic channel will likely impact alldata streams transmitted from the base station to the mobile station ina similar manner and thus a single (or common) stream of power controlcommands can be used to control the transmit power of all data streamstransmitted to the given mobile station from the base station.

[0049] Referring still to FIG. 1A, the data streams 122, 122 a receivedfrom BS2 are provided to a power control command generator 132 whichgenerates a single stream of power control commands from the receiveddata streams. In the embodiment of FIG. 1A, power control commandgenerator 132 optionally selects either data stream 122 or data stream122 a (or a combination thereof) to monitor. Thereafter, the powercontrol command generator 132 monitors either the receivedsignal-to-noise ratio or the frame error rate associated with theselected data stream (or the sum of the received signal-to-noise ratioor the frame error rate associated with both data streams 122, 122 a ifthe combination is being monitored), and generates a series of forwardlink power control commands 142 based on this information. Each powercontrol command in stream 142 will, for example, represent a command tothe BS2 indicating that the BS2 should either increase or decrease thetransmit power level used to transmit subsequent frames of data streams122, 122 a to mobile radio station 100. Again, deriving such a stream ofpower control commands using either the received signal-to-noise ratioor the frame error rate of a single received signal is well known in theart. Where a combination of data streams 122, 122 a is being monitored,the sum of the received signal-to-noise ratios associated with each datastream is preferably compared to a threshold representing a desired sumof signal-to-noise ratios expected from the combination of data streams122, 122 a in order to generate the stream of power control commands. Inthe embodiment of FIG. 1A, a single, common stream of power controlcommands 142 is generated for both data streams 122, 122 a using eitherone of the two data streams or both streams.

[0050] The data streams 124, 124 a received from BSn are provided to apower control command generator 134 which generates a single stream ofpower control commands from the received data streams. In the embodimentof FIG. 1A, power control command generator 134 optionally selectseither data stream 124 or data stream 124 a (or a combination thereof)to monitor. Thereafter, the power control command generator 134 monitorseither the received signal-to-noise ratio or the frame error rateassociated with the selected data stream (or the sum of the receivedsignal-to-noise ratio or the frame error rate associated with both datastreams 124, 124 a if the combination is being monitored), and generatesa series of forward link power control commands 144 based on thisinformation. Each power control command in stream 144 will, for example,represent a command to the BSn indicating that the BSn should eitherincrease or decrease the transmit power level used to transmitsubsequent frames of data streams 124, 124 a to mobile radio station100. Again, deriving such a stream of power control commands usingeither the received signal-to-noise ratio or the frame error rate of asingle received signal is well known in the art. Where a combination ofdata streams 124, 124 a is being monitored, the sum of the receivedsignal-to-noise ratios associated with each data stream is preferablycompared to a threshold representing a desired sum of signal-to-noiseratios expected from the combination of data streams 124, 124 a in orderto generate the stream of power control commands. In the embodiment ofFIG. 1A, a single, common stream of power control commands 144 isgenerated for both data streams 124, 124 a using either one of the twodata streams or both streams.

[0051] Although data streams from three base stations are shown as beingreceived by mobile station 100 a, it will be understood by those skilledin the art that mobile station 100 could be configured to receive datasignals from more than (or less than) three different base stations.

[0052] The power control command streams 140, 142, 144 are provided to amutliplexer 146 which is controlled by an interleaver controller 148.The mutliplexer 146 merges the separate power control command streams140, 142, 144 into a single interleaved power control bit stream 110. Atransmitter 150 transmits the interleaved power control bit stream 110back to the base stations (BS1, BS2. BSn) on a power control channel orsubchannel.

[0053] In a preferred embodiment of the present invention, each basestation in a first set of active base stations simultaneously transmitsa version of a first data stream (e.g., signals 120, 122 and 124 in FIG.1A) to mobile station 100, and each base station in a second set ofactive base stations simultaneously transmits a version of a second datastream (e.g., signals 120 a, 122 a and 124 a) to mobile station 100. Thebase stations in each active set are preferably maintained by monitoringpilot signals from base stations in the vicinity of the mobile station100, and then adding or deleting a base station from the active set asthe pilot signal from the base station either rises above or falls belowa threshold. Using pilot signals from base stations for maintaining anactive set of base stations is well known in the art. In the preferredembodiment, the sets of active base stations need not be identical;however, one of the sets of active base stations (e.g., the second set)will typically be a subset of the other set of active base stations(e.g., the first set). As set forth below, in some embodiments of theinvention, the second active set of base stations will not be a subsetof the first active set.

[0054] In FIG. 1A, the first set of active base stations used tosimultaneously transmit versions of the first data stream (e.g., signals120, 122 and 124 in FIG. 1A) to the mobile station was identical to thesecond set of active base stations used to simultaneously transmitversions of the second data stream (e.g., signals 120 a, 122 a and 124a) to the mobile station. FIG. 1B shows an alternate preferredembodiment of the mobile radio station of FIG. 1A where different setsof active base stations are transmitting the different data streams tothe mobile radio station. In FIG. 1B, mobile radio station 100 b isreceiving different data streams 120, 120 a from BS1, only a single datastream 122 from BS2 and only a single data stream 124 from BSn. Thus, inFIG. 1B, a first active set of base stations (i.e., BS1, BS2 and BSn)simultaneously transmit versions of a first data stream (i.e., signals120, 122 and 124 in FIG. 1B) to mobile station 100 b, and a second setof active base stations formed only of BS1 transmits a second datastream (i.e., signal 120) to mobile station 100 a. The active sets ofbase stations used for transmitting the data streams to the mobilestation may not be identical as shown in FIG. 1B when, for example, themobile station is in a soft handoff between different base stations inthe active sets. In the embodiment shown in FIG. 1B, power controlcommand generators 132 a, 134 a, respectively monitor data streams 122,124 in order to generate power control command streams 142, 144 asdescribed above.

[0055]FIG. 1C shows a mobile radio station 100 c that generates aninterleaved power control signal 110 for controlling the transmit powerlevels of a plurality of different data streams transmitted to themobile station from one or more base stations, in accordance with analternate preferred embodiment of the present invention. In contrast tothe embodiments of FIGS. 1A and 1B, in the embodiment of FIG. 1C, thetransmit power levels of different data streams transmitted to themobile station from the same base station are controlled using differentstreams of power control commands included in the interleaved powercontrol signal.

[0056] Thus, in mobile station 100 c, the data streams 120, 120 areceived from BS1 are provided to a power control command generator 131which generates a different stream of power control commands for each ofthe received data streams. Power control command generator 131 monitorsthe received signal-to-noise ratio or the frame error rate associatedwith data stream 120, and generates a series of forward link powercontrol commands 140 a based on this information. Power control commandgenerator 131 also separately monitors the received signal-to-noiseratio or the frame error rate associated with data stream 120 a, andgenerates a separate series of forward link power control commands 140 bbased on this information. Each power control command in stream 140 a or140 b will, for example, represent a command to the BS1 indicating thatthe BS1 should either increase or decrease the transmit power level usedto transmit subsequent frames of data streams 120, 120 a to mobile radiostation 100. Deriving such a stream of power control commands usingeither the received signal-to-noise ratio or the frame error rate of areceived signal is well known in the art.

[0057] Referring still to FIG. 1C, the data streams 122, 122 a receivedfrom BS2 are provided to a power control command generator 133 whichgenerates a different stream of power control commands for each of thereceived data streams. Power control command generator 133 monitors thereceived signal-to-noise ratio or the frame error rate associated withdata stream 122, and generates a series of forward link power controlcommands 142 a based on this information. Power control commandgenerator 133 also separately monitors the received signal-to-noiseratio or the frame error rate associated with data stream 122 a, andgenerates a separate series of forward link power control commands 142 bbased on this information. Each power control command in stream 142 a or142 b will, for example, represent a command to the BS2 indicating thatthe BS2 should either increase or decrease the transmit power level usedto transmit subsequent frames of data streams 122, 122 a to mobile radiostation 100.

[0058] The data streams 124, 124 a received from BSn are provided to apower control command generator 135 which generates a different streamof power control commands for each of the received data streams. Powercontrol command generator 135 monitors the received signal-to-noiseratio or the frame error rate associated with data stream 124, andgenerates a series of forward link power control commands 144 a based onthis information. Power control command generator 135 also separatelymonitors the received signal-to-noise ratio or the frame error rateassociated with data stream 124 a, and generates a separate series offorward link power control commands 144 b based on this information.Each power control command in stream 144 a or 144 b will, for example,represent a command to the BSn indicating that the BSn should eitherincrease or decrease the transmit power level used to transmitsubsequent frames of data streams 124, 124 a to mobile radio station100.

[0059] Although data streams from three base stations are shown as beingreceived by mobile station 100 c, it will be understood by those skilledin the art that mobile station 100 c could be configured to receive datasignals from more than (or less than) three different base stations.

[0060] The power control command streams 140 a, 140 b, 142 a, 142 b, 144a, 144 b are provided to a mutliplexer 146 which is controlled by aninterleaver controller 148. The mutliplexer 146 merges the separatepower control command streams 140 a, 140 b, 142 a, 142 b, 144 a, 144 binto a single interleaved power control bit stream 110. A transmitter150 transmits the interleaved power control bit stream 110 back to thebase stations (BS1, BS2. BSn) on a power control channel or subchannel.

[0061] In FIG. 1C, the first set of active base stations used tosimultaneously transmit versions of the first data stream (e.g., signals120, 122 and 124 in FIG. 1C) to the mobile station was identical to thesecond set of active base stations used to simultaneously transmitversions of the second data stream (e.g., signals 120 a, 122 a and 124a) to the mobile station. FIG. 1D shows an alternate preferredembodiment of the mobile radio station of FIG. 1C where different setsof active base stations are transmitting the different data streams tothe mobile radio station. In FIG. 1D, mobile radio station 100 d isreceiving different data streams 120, 120 a from BS1, only a single datastream 122 from BS2 and only a single data stream 124 from BSn. Thus, inFIG. 1D, a first active set of base stations (i.e., BS1, BS2 and BSn)simultaneously transmit versions of a first data stream (i.e., signals120, 122 and 124 in FIG. 1D) to mobile station 10 d, and a second set ofactive base stations formed only of BS1 transmits a second data stream(i.e., signal 120) to mobile station 10 d. The active sets of basestations used for transmitting the data streams to the mobile stationmay not be identical as shown in FIG. 1D when, for example, the mobilestation is in a soft handoff between different base stations in theactive sets. In the embodiment shown in FIG. 1D, power control commandgenerators 133 a, 135 a, respectively monitor data streams 122, 124 inorder to generate power control command streams 142 a, 144 a asdescribed above.

[0062]FIG. 1E shows a mobile radio station 100 e that forms aninterleaved power control bit stream in accordance with an alternateembodiment of the present invention. In this embodiment, a first set ofactive base stations (BS1, BS2, . . . BSn) simultaneously transmitversions of the first data stream (e.g., signals 120, 122 and 124) tothe mobile station 100 e, and a second set of active base stations (BS1,BS2, . . . BSm) simultaneously transmit versions of the second datastream (e.g., signals 120 a, 122 a and 125) to the mobile station 10 e.Power control command generator 160 generates a separate stream of powercontrol commands for controlling the first data stream from each basestation in the first active set. Thus, power control command stream 160a is used for controlling the transmit power of the first data streamfrom BS1; power control command stream 160 b is used for controlling thetransmit power of the first data stream from BS2; and power controlcommand stream 160 n is used for controlling the transmit power of thefirst data stream from BSn.

[0063] Power control command generator 160 forms each output powercontrol command stream (i.e., streams 160 a, 160 b, . . . 160 n) bymonitoring the signal quality of the first data stream received frommultiple base stations in the first active set. Thus, for example, thepower control command stream 160 b for controlling the transmit powerlevel of the first data stream 122 from the second base station (BS2) isformed by monitoring the signal quality of the first data stream 122received from the second base station (BS2) as well as the signalquality of the first data stream 120 received from the first basestation (BS1) and the signal quality of first data stream 124 receivedfrom base station BSn. Similarly, the power control command stream 160 afor controlling the transmit power level of the first data stream 120from the first base station (BS1) is formed by monitoring the signalquality of the first data stream 120 received from the first basestation (BS1) as well as the signal quality of the first data stream 122received from the second base station (BS2) and the signal quality offirst data stream 124 received from base station BSn.

[0064] In one embodiment, the algorithm used by power control commandgenerator 160 for generating each stream of power control commands 160a, 160 b, . . . 160 n, is as follows. Initially, power control commandgenerator 160 identifies the base station (BShighest) in the firstactive set that is providing the highest total signal-to-noise ratio(SNR) for the first data stream to mobile station 100 e. Next, a totalvalue representing the sum of the SNRs for the first data streamreceived from each base station in the first active set is compared to athreshold that represents a desired total SNR value that mobile station100 e expects to receive from all base stations in the first active setfor the first data stream. Based on this comparison, power controlcommand generator 160 generates a power control command (i.e., a powerup, power down or power hold command) for the first data stream fromBShighest and this power control command (PCBS-Highest) is then sent toBShighest using the power control command stream associated withBShighest, i.e., either stream 160 a, 160 b, or . . . , 160 n. Next, thepower control command generator 160 generates a first predicted SNRvalue representing the sum of the SNRs for the first data stream thatmobile station 100 e expects to receive from all base stations in thefirst active set after PCBS-Highest is processed by BShighest. Powercontrol command generator 160 also identifies the base station(BSsecond-highest) in the first active that is providing the secondhighest total SNR for the first data stream to mobile station 10 e.Thereafter, the first predicted SNR value is compared to the thresholddescribed above, and, based on this comparison, power control commandgenerator 160 generates a power control command (i.e., a power up, powerdown or power hold command) for the first data stream fromBSsecond-highest and this power control command (PCBS-Second-Highest) isthen sent to BSsecond-highest using the power control command streamassociated with BSsecond-highest, i.e., either stream 160 a, 160 b, or .. . , 160 n. Next, the power control command generator 160 generates asecond predicted SNR value representing the sum of the SNRs for thefirst data stream that mobile station 10 e expects to receive from allbase stations in the first active set after PCBS-Highest andPCBS-Second-Highest are processed by BShighest and BSsecond-highest.Power control command generator 160 also identifies the base station(BSthird-highest) in the first active that is providing the thirdhighest total SNR for the first data stream to mobile station 10 e.Thereafter, the second predicted SNR value is compared to the thresholddescribed above, and, based on this comparison, power control commandgenerator 160 generates a power control command (i.e., a power up, powerdown or power hold command) for the first data stream fromBSthird-highest and this power control command (PCBS-Third-Highest) isthen sent to BSthird-highest using the power control command streamassociated with BSthird-highest, i.e., either stream 160 a, 160 b, or .. . , 160 n. This process is then repeated as described above in aniterative manner until power control command generator 160 has generateda power control command for each base station in the first active set.

[0065] Referring still to FIG. 1E, power control command generator 162generates a single (common) stream of power control commands 162 a forcontrolling the second data stream from each base station in the secondactive set. Thus, power control command stream 162 a is used forcontrolling the transmit power of the second data stream from BS2, thetransmit power of the second data stream from BS2, and the transmitpower of the second data stream from BSm. Power control commandgenerator 162 forms power control command stream 162 by simultaneouslymonitoring the signal quality of the second data stream received fromall base stations in the second active set. In one embodiment, thealgorithm used by power control command generator 162 for generating thestream of power control commands 162 a is as follows. Power controlcommand generator 162 calculates a total value representing the sum ofthe SNRs for the second data stream received from each base station inthe second active set. This sum is compared to a threshold thatrepresents a desired total SNR value that mobile station 100 e expectsto receive from all base stations in the second active set for thesecond data stream. Based on this comparison, power control commandgenerator 162 generates a power control command (i.e., a power up, powerdown or power hold command) for the second data stream and this powercontrol command is then sent to the base stations in the second activeset using stream 162 a.

[0066] The power control command streams 160 a, 160 b, . . . 160 n and162 a are provided to a mutliplexer 146 which is controlled by aninterleaver controller 148. The mutliplexer 146 merges the separatepower control command streams into a single interleaved power controlbit stream 110. A transmitter 150 transmits the interleaved powercontrol bit stream 110 back to the base stations in the first and secondactive sets on a power control channel or subchannel.

[0067]FIG. 1F shows a mobile radio station 100 f that forms aninterleaved power control bit stream in accordance with a furtheralternate embodiment of the present invention. In this embodiment, afirst set of active base stations (BS1, BS2) simultaneously transmitversions of the first data stream (e.g., signals 120, 122) to the mobilestation 100 f, and a second set of active base stations (BS1) transmitthe second data stream (signal 120 a) to the mobile station 100 f. Inthis embodiment, the transmit power level of the first data stream 122from the second base station (BS2) is controlled at the mobile station100 f by monitoring the signal quality of the first data stream 120received from the first base station as well as the signal quality ofthe first data stream 122 received from the second base station.However, in contrast to the embodiment of FIG. 1E, in this embodimentthe transmit power levels of the first and second data streams (120, 120a) from the first base station are controlled at the mobile station bymonitoring the signal quality of only the second data stream 120 areceived from the first base station.

[0068] Referring still to FIG. 1F, power control command generator 170forms output power control command stream 170 a by monitoring the signalquality of the first data stream received from multiple base stations inthe first active set. Thus, for example, the power control commandstream 170 a for controlling the transmit power level of the first datastream 122 from the second base station (BS2) is formed by monitoringthe signal quality of the first data stream 122 received from the secondbase station (BS2) as well as the signal quality of the first datastream 120 received from the first base station (BS1). In oneembodiment, the algorithm used by power control command generator 170for generating the stream of power control commands 170 a is as follows.Power control command generator 170 calculates a total valuerepresenting the sum of the SNRs for the first data stream received fromeach base station in the first active set. This sum is compared to athreshold that represents a desired total SNR value that mobile station100 f expects to receive from all base stations in the first active setfor the first data stream. Based on this comparison, power controlcommand generator 170 generates a power control command (i.e., a powerup, power down or power hold command) that is then sent using stream 170a.

[0069] Power control command generator 172 monitors either the receivedsignal-to -noise ratio or the frame error rate associated with thesecond data stream 120 a from the first base station, and generates astream of forward link power control commands 172 a based on thisinformation. As set forth above, deriving such a stream of power controlcommands using either the received signal-to-noise ratio or the frameerror rate of a received signal is well known in the art.

[0070] The power control command streams 170 a and 172 a are provided toa mutliplexer 146 which is controlled by an interleaver controller 148.The mutliplexer 146 merges the separate power control command streamsinto a single interleaved power control bit stream 110. A transmitter150 transmits the interleaved power control bit stream 110 back to thebase stations in the first and second active sets on a power controlchannel or subchannel.

[0071]FIG. 1G shows a mobile radio station 100 g that forms aninterleaved power control bit stream in accordance with a furtheralternate embodiment of the present invention. Again, in thisembodiment, a first set of active base stations (BS1, BS2, . . . BSn)simultaneously transmit versions of a first data stream to the mobilestation 100 g, and a second set of active base stations (BS1, BS2, . . .BSm) simultaneously transmit versions of a second data stream to themobile station 100 g. In this embodiment, a first (common) power controlcommand stream 180 a is generated from the versions of the first datastream transmitted from each base station in the second active set(collectively labeled 121) and from the versions of the second datastream transmitted from each base station in the second active set(collectively labeled 123). Power control command stream 180 a is thenused for controlling the transmit power level of the second data streamfrom each base station in the second active set (collectively labeled121) and the first data stream from each base station in the secondactive set (collectively labeled 123). A second (common) power controlstream 182 a is generated from the first data stream from each basestation in the first active set and not in the second active set(collectively labeled 125), and then used for controlling the transmitpower level of the first data stream from each base station in the firstactive set and not in the second active set.

[0072] Referring still to FIG. 1G, power control command generator 180forms a single (common) output power control command stream 180 a bysimultaneously monitoring the signal quality of traffic signals 121 and123 which respectively represent the first data stream transmitted fromeach base station in the second active set and the second data streamtransmitted from each base station in the second active set. In oneembodiment, the algorithm used by power control command generator 180for generating the stream of power control commands 180 a is as follows.Power control command generator 180 calculates a total valuerepresenting the sum of the SNRs for the first data stream received fromeach base station in the second active set (i.e., streams 121). This sumis compared to a first threshold that represents a desired total SNRvalue that mobile station 100 g expects to receive from all basestations in the second active set for the first data stream. Powercontrol command generator 180 also calculates a total value representingthe sum of the SNRs for the second data stream received from each basestation in the second active set (i.e., streams 123). This sum iscompared to a second threshold that represents a desired total SNR valuethat mobile station 100 g expects to receive from all base stations inthe second active set for the second data stream. If, in either of theabove comparisons the threshold has not been exceeded, power controlcommand generator 180 generates a power-up that is then sent usingstream 180 a; alternatively, if in either of the above comparisons thethreshold has been exceeded, power control command generator 180generates a power-down that is then sent using stream 180 a.

[0073] Power control command generator 182 forms a single (common)output power control command stream 182 a by simultaneously monitoringthe signal quality of traffic signals 125 which respectively representthe first data stream transmitted from each base station in the firstactive set and not in the second active set. In one embodiment, thealgorithm used by power control command generator 182 for generating thestream of power control commands 182 a is as follows. Power controlcommand generator 182 calculates a total value representing the sum ofthe SNRs for the first data stream received from each base station inthe first active set and not in the second active set. This sum iscompared to a threshold that represents a desired total SNR value thatmobile station 100 g expects to receive from all base stations in thefirst active set and not in the second active set for the first datastream. Based on this comparison, power control command generator 182generates a power control command (i.e., a power up, power down or powerhold command) that is then sent using stream 182 a. The power controlcommand streams 180 a and 182 a are provided to a mutliplexer 146 whichis controlled by an interleaver controller 148. The mutliplexer 146merges the separate power control command streams into a singleinterleaved power control bit stream 110. A transmitter 150 transmitsthe interleaved power control bit stream 110 back to the base stationsin the first and second active sets on a power control channel orsubchannel.

[0074]FIG. 1H shows a mobile radio station 100 h that forms aninterleaved power control bit stream in accordance with a stillalternate embodiment of the present invention. Again, in thisembodiment, a first set of active base stations (BS1, BS2, . . . BSn)simultaneously transmit versions of a first data stream to the mobilestation 100 h, and a second set of active base stations (BS1, BS2, . . .BSm) simultaneously transmit versions of a second data stream to themobile station 10 h. In this embodiment, a first (common) power controlcommand stream 184 a is generated from the versions of the first datastream transmitted from each base station in the first active set(collectively labeled 177). Power control command stream 184 a containscoarse power control commands. As explained more fully below, the coarsepower control command stream 184 a is used for controlling the transmitpower level of the first and second data streams from each base stationin the first and second active sets (collectively labeled 177, 178). Asecond (common) power control stream 186 a is generated from the firstdata stream from each base station in the second active set(collectively labeled 177 a). Signals 177 a represent a subset ofsignals 170. Power control command stream 186 a contains fine powercontrol commands. As explained more fully below, the fine power controlcommand stream 186 a is used, in combination with the coarse powercontrol command stream 184 a, for controlling the transmit power levelof the second data stream transmitted from each base station in thesecond active set (signals 178) and for controlling the transmit powerlevel of the first data stream transmitted from each base station in thesecond active set (signals 177 a).

[0075] Referring still to FIG. 1H, power control command generator 184forms a single (common) coarse power control command stream 184 a bysimultaneously monitoring the signal quality of traffic signals 177which represent the first data stream transmitted from each base stationin the first active set. In one embodiment, the algorithm used by powercontrol command generator 184 for generating the stream of power controlcommands 184 a is as follows. Power control command generator 184calculates a total value representing the sum of the SNRs for the firstdata stream received from each base station in the first active set.This sum is compared to a threshold that represents a desired total SNRvalue that mobile station 100 h expects to receive from all basestations in the first active set for the first data stream. Based onthis comparison, power control command generator 184 generates a powercontrol command (i.e., a power up, power down or power hold command)that is then sent using stream 184 a.

[0076] In one embodiment, the algorithm used by power control commandgenerator 184 for generating the stream of power control commands 184 ais as follows. Power control command generator 184 calculates a totalvalue representing the sum of the SNRs for the first data streamreceived from each base station in the first active set. This sum iscompared to a threshold that represents a desired total SNR value thatmobile station 100 h expects to receive from all base stations in thefirst active set for the first data stream. Based on this comparison,power control command generator 184 generates a power control command(i.e., a power up, power down or power hold command) that is then sentusing stream 184 a.

[0077] Power control command generator 186 forms a single (common) finepower control command stream 186 a by simultaneously monitoring thesignal quality of traffic signals 177 a and 178 which respectivelyrepresent the first data stream transmitted from each base station inthe second active set and the second data stream transmitted from eachbase station in the second active set. In one embodiment, the algorithmused by power control command generator 186 for generating the stream ofpower control commands 186 a is as follows. Power control commandgenerator 186 calculates a total value representing the sum of the SNRsfor the first data stream received from each base station in the secondactive set (i.e., streams 177 a only). This sum is compared to athreshold that represents a desired total SNR value that mobile station100 h expects to receive from all base stations in the second active setfor the first data stream. Based on this comparison, power controlcommand generator 186 generates a power control command (i.e., a powerup, power down or power hold command) that is then sent using stream 186a.

[0078] In an alternate embodiment, a different algorithm is used bypower control command generator 186 for generating the stream of powercontrol commands 186 a. In this alternate embodiment, power controlcommand generator 186 calculates a total value representing the scaledsum of the SNRs for the first data stream received from each basestation in the second active set and the SNRs for the second data streamfrom each base station in the second active set (i.e., streams 177 a and178). This sum is compared to a threshold that represents a desiredtotal SNR value that mobile station 100 h expects to receive from basestations in the second active set for the first data stream and frombase stations in the second active set for the second data stream. Basedon this comparison, power control command generator 186 generates apower control command (i.e., a power up, power down or power holdcommand) that is then sent using stream 186 a.

[0079] The power control command streams 184 a and 186 a are provided toa mutliplexer 146 which is controlled by an interleaver controller 148.The mutliplexer 146 merges the separate power control command streamsinto a single interleaved power control bit stream 110. A transmitter150 transmits the interleaved power control bit stream 110 back to thebase stations in the first and second active sets on a power controlchannel or subchannel.

[0080]FIG. 1I shows a mobile radio station 100 i that forms aninterleaved power control bit stream in accordance with a stillalternate embodiment of the present invention. Again, in thisembodiment, a first set of active base stations (BS1, BS2, BSn)simultaneously transmit versions of a first data stream to the mobilestation 100 i, and a second set of active base stations (BS1, BS2, . . .BSm) simultaneously transmit versions of a second data stream to themobile station 100 i. In this embodiment, a first (common) power controlcommand stream 188 a is generated from the versions of the first datastream transmitted from each base station in the first active set(collectively labeled 177) and from the versions of the second datastream transmitted from each base station in the second active set(collectively labeled 178). Power control command stream 188 a containscoarse power control commands. As explained more fully below, the coarsepower control command stream 188 a is used for controlling the transmitpower level of the first and second data streams from each base stationin the first and second active sets (collectively labeled 177, 178). Asecond (common) power control stream 188 b is generated from the firstdata stream from each base station in the first active set (signals 177)and from the second data stream from each base station in the secondactive set (signals 178.) Power control command stream 186 b containsfine power control commands. As explained more fully below, the finepower control command stream 188 b is used, in combination with thecoarse power control command stream 188 a, for controlling the transmitpower level of the second data stream transmitted from each base stationin the second active set and not in the first active set.

[0081] Referring still to FIG. 1I, power control command generator 188forms the single (common) coarse power control command stream 188 a andthe single (common) fine power control command stream 188 b bysimultaneously monitoring the signal quality of traffic signals 177, 178which respectively represent the first data stream transmitted from eachbase station in the first active set and the second data stream fromeach base station in the second active set. In one embodiment, thealgorithm used by power control command generator 188 for generating thestream of power control commands 188 a is as follows. Power controlcommand generator 188 calculates a total value representing the sum ofthe SNRs for the first data stream received from each base station inthe first active set (i.e., streams 177 only). This sum is compared to athreshold that represents a desired total SNR value that mobile station100 i expects to receive from all base stations in the first active setfor the first data stream. Based on this comparison, power controlcommand generator 188 generates a power control command (i.e., a powerup, power down or power hold command) that is then sent using stream 188a.

[0082] In one embodiment, the algorithm used by power control commandgenerator 188 for generating power control command stream 188 b is asfollows. First, power control command generator 188 calculates a totalvalue representing the sum of the SNRs for the second data streamreceived from each base station in the second active set (i.e., streams178 only). Next, this sum is adjusted based on the last power controlcommand sent using stream 188 a. More particularly, the power controlcommand generator 180 generates a predicted SNR value representing thesum of the SNRs for the second data stream that mobile station 100 iexpects to receive from all base stations in the second active after theprevious power control command sent on stream 188 a is processed by suchbase stations. The predicted SNR value is then compared to a thresholdthat represents a desired total SNR value that mobile station 100 iexpects to receive from all base stations in the second active set forthe second data stream. Based on this comparison, power control commandgenerator 188 generates a power control command (i.e., a power up, powerdown or power hold command) for the second data stream from each basestation in the second active set, and this power control command is sentusing power control command stream 188 b.

[0083] The power control command streams 188 a and 188 b are provided toa mutliplexer 146 which is controlled by an interleaver controller 148.The mutliplexer 146 merges the separate power control command streamsinto a single interleaved power control bit stream 110. A transmitter150 transmits the interleaved power control bit stream 110 back to thebase stations in the first and second active sets on a power controlchannel or subchannel.

[0084] In an alternate embodiment of the mobile station shown in FIG.1I, power control command stream 188 a is used for controlling the firstand second data streams from base stations that are in the first activeset and not in the second active set.

[0085] Referring now to FIG. 2A, there is shown the components of a basestation 200 a that receives a plurality of interleaved power controlsignals from a plurality of mobile stations (MS1, MS2 . . . MSm), anduses the power control signals to control the transmit power levels ofdifferent data streams transmitted to the mobile stations, in accordancewith a preferred embodiment of the present invention. In the embodimentof FIG. 2A, the transmit power levels of different data streamstransmitted to a mobile station 100 a (as shown in FIG. 1A) from basestation 200 a are controlled using a common stream of power controlcommands included in an interleaved power control signal received atbase station 200 a. Interleaved power control signals 110 received fromthe mobile stations (MS1, MS2, . . . MSm) are provided to power controlsignal demodulation units 210, 212, 214. Demodulation unit 210demodulates an interleaved power control signal 110 transmitted to basestation 200 from a first mobile station (MS1), demodulation unit 212demodulates an interleaved power control signal 110 transmitted to basestation 200 from a second mobile station (MS2), and demodulation unit214 demodulates an interleaved power control signal transmitted to basestation 200 from a further mobile station (MSn). In the embodiment shownin FIG. 2A, each interleaved power stream 110 is formed using a mobilestation such as mobile station 100 a wherein a common stream of powercontrol commands are included in an interleaved power control signal 110in order to control the transmit power levels of different data streamstransmitted to the mobile station from the same base station.

[0086] The output of demodulation unit 210 is provided to ademultiplexer 220 which deinterleaves the power control signal from thefirst mobile station (MS1) in order to extract a power control bitstream 230 representative of the stream of power control commands 140transmitted to base station 200 from the first mobile station (MS1). Thepower control bit stream 230 is used to control the gain (or transmitpower level) of transmitters 240, 242, which respectively transmit firstand second different data streams 120, 120 a back to the first mobilestation (MS1). The output of demodulation unit 212 is provided to ademultiplexer 222 which deinterleaves the power control signal from asecond mobile station (MS2) in order to extract a power control bitstream 232 representative of a stream of power control commandstransmitted to base station 200 from the second mobile station (MS2).The power control bit stream 232 is used to control the gain (ortransmit power level) of transmitters 244, 246, which respectivelytransmit different data streams back to the second mobile station (MS2).Similarly, the output of demodulation unit 214 is provided to ademultiplexer 224 which deinterleaves the power control signal from afurther mobile station (MSm) in order to extract a power control bitstream 234 representative of a stream of power control commandstransmitted to base station 200 from the further mobile station (MSm).The power control bit stream 234 is used to control the gain (ortransmit power level) of transmitters 248, 250, which respectivelytransmit different data streams back to the further mobile station(MSm). In one embodiment, each of the demodulation units 210, 212, 214is configured to receive an interleaved power control signal on adifferent one of a plurality of power control subchannels, wherein eachof the plurality of power control subchannels is associated with adifferent mobile station in the mobile radio communication system.

[0087] Although power control signals from three mobile stations 100 aare shown as being received by base station 200 a, it will be understoodby those skilled in the art that base station 200 a could be configuredto receive power control signals from more than (or less than) threedifferent mobile stations.

[0088]FIG. 2B shows an alternate preferred embodiment of the basestation of FIG. 2A. In FIG. 2B, base station 200 b transmits a pluralityof different data streams 120, 120 a to a first mobile station (MS1),and only a single data stream to other mobile stations (MS2, MSm) on thebase station's forward link. Thus, in base station 200 b, the powercontrol bit stream 232 is used to control the gain (or transmit powerlevel) of a single transmitter 244 which transmits one data stream backto the second mobile station (MS2), and power control bit stream 234 isused to control the gain of a single transmitter 248 which transmits onedata stream back to the further mobile station (MSm). The signal outputby transmitter 244 in FIG. 2B may correspond, for example, to the firstdata stream 122 from BS2 that is provided to the power control commandgenerator 132 a in FIG. 1B, because in the mobile station of FIG. 1Bonly the first data stream (and not the second stream) is provided tomobile station 100 b from BS2.

[0089] Referring now to FIG. 2C, there is shown the components of a basestation 200 c that receives a plurality of interleaved power controlsignals from a plurality of mobile stations (MS1, MS2 . . . MSm), anduses the power control signals to control the transmit power levels ofdifferent data streams transmitted to the mobile stations, in accordancewith an alternative preferred embodiment of the present invention. Inthe embodiment of FIG. 2C, the transmit power levels of different datastreams transmitted to a mobile station 100 c (as shown in FIG. 1C) frombase station 200 c are controlled using different streams of powercontrol commands included in an interleaved power control signalreceived at base station 200 c. Interleaved power control signals 110received from the mobile stations (MS1, MS2, . . . MSm) are provided topower control signal demodulation units 210, 212, 214. Demodulation unit210 demodulates an interleaved power control signal 110 transmitted tobase station 200 c from a first mobile station (MS1), demodulation unit212 demodulates an interleaved power control signal 110 transmitted tobase station 200 from a second mobile station (MS2), and demodulationunit 214 demodulates an interleaved power control signal transmitted tobase station 200 from a further mobile station (MSn). In the embodimentshown in FIG. 2C, each interleaved power stream 110 is formed using amobile station such as mobile station 100 c wherein different streams ofpower control commands are included in an interleaved power controlsignal 110 in order to control the transmit power levels of differentdata streams transmitted to the mobile station from the same basestation.

[0090] In FIG. 2C, the output of demodulation unit 210 is provided to ademultiplexer 220 which deinterleaves the power control signal from thefirst mobile station (MS1) in order to extract power control bit streams230 a, 230 b which are respectively representative of the streams ofpower control commands 140 a, 140 b transmitted to base station 200 cfrom the first mobile station (MS1). The power control bit streams 230a, 230 b are used to control the gain (or transmit power level) oftransmitters 240, 242, which respectively transmit first and seconddifferent data streams 120, 120 a back to the first mobile station(MS1). The output of demodulation unit 212 is provided to ademultiplexer 222 which deinterleaves the power control signal from asecond mobile station (MS2) in order to extract power control bitstreams 232 a, 232 b which are respectively representative of streams ofpower control commands transmitted to base station 200 b from the secondmobile station (MS2). The power control bit streams 232 a, 232 b areused to control the gain (or transmit power level) of transmitters 244,246, which respectively transmit different data streams back to thesecond mobile station (MS2). Similarly, the output of demodulation unit214 is provided to a demultiplexer 224 which deinterleaves the powercontrol signal from a further mobile station (MSm) in order to extractpower control bit streams 234 a, 234 b representative of streams ofpower control commands transmitted to base station 200 c from thefurther mobile station (MSm). The power control bit streams 234 a, 234 bare used to control the gain (or transmit power level) of transmitters248, 250, which respectively transmit different data streams back to thefurther mobile station (MSm).

[0091]FIG. 2D shows an alternate preferred embodiment of the basestation of FIG. 2C. In FIG. 2D, base station 200 d transmits a pluralityof different data streams 120, 120 a to a first mobile station (MS1),and only a single data stream to other mobile stations (MS2, MSm) on thebase station's forward link.). The signal output by transmitter 244 inFIG. 2D may correspond, for example, to the first data stream 122 fromBS2 that is provided to the power control command generator 133 a inFIG. 1D, because in the mobile station of FIG. 1D only the first datastream (and not the second stream) is provided to mobile station 100 dfrom BS2.

[0092] A communication system operating in accordance with the presentinvention may be formed of one or more mobile stations configured inaccordance with mobile stations 100 a or 100 b that receive data trafficsignals from and transmit interleaved power control signals to aplurality of different base stations configured in accordance with basestations 200 a or 200 b. Alternatively, a communication system operatingin accordance with the present invention is formed of one or more mobilestations configured in accordance with mobile stations 100 c or 100 dthat receive data traffic signals from and transmit interleaved powercontrol signals to a plurality of different base stations configured inaccordance with base stations 200 c or 200 d.

[0093] In a still further alternative, a communication system operatingin accordance with the present invention is formed of one or more mobilestations configured in accordance with mobile station 100 e that receivedata traffic signals from and transmit interleaved power control signalsto a plurality of different base stations configured substantially inaccordance with base stations 200 d except, in this embodiment 230, 232a, 234 a and 230 b shown in FIG. 2D would correspond to signals 160 a,160 b, 160 c and 162 produced from a mobile station of the form shown inFIG. 1E.

[0094]FIG. 2E shows a base station 200 e that receives a plurality ofpower control signals formed from a plurality of mobile stations 100 fof the form shown in FIG. 1F, and uses the power control signals tocontrol the transmit power levels of first and second data streamstransmitted to the mobile stations 100 f. In the embodiment of FIG. 2E,base station 200 e is in the both active sets of the two mobile stations100 f shown as being serviced by the base station. Power control signalsreceived from the mobile stations (MS1, . . . MSx) are provided to powercontrol signal demodulation units 210, 214. Demodulation unit 210demodulates an interleaved power control signal transmitted to basestation 200 e from a first mobile station (MS1), demodulation unit 214demodulates an interleaved power control signal 110 transmitted to basestation 200 e from a second mobile station (MSx).

[0095] The output of demodulation unit 210 is provided to ademultiplexer 221 which deinterleaves the power control signal from thefirst mobile station (MS1) in order to extract a power control bitstream 250 representative of the stream of power control commands 172 atransmitted to base station 200 e from a first mobile station of theform 100 f (as shown in FIG. 1F). The power control bit stream 250 isused to control the gain (or transmit power level) of transmitters 240,242, which respectively transmit first and second different data streams120, 120 a back to the first mobile station (MS1). The output ofdemodulation unit 214 is provided to a demultiplexer 225 whichdeinterleaves the power control signal from a second mobile station ofthe form 100 f (as shown in FIG. 1) in order to extract a power controlbit stream 252 representative of a further stream of power controlcommands 172 a transmitted to base station 200 e from the second mobilestation (MS2). The power control bit stream 252 is used to control thegain (or transmit power level) of transmitters 248, 249, whichrespectively transmit first and second different data streams back tothe second mobile station (MS2). In one embodiment, each of thedemodulation units 210,214 is configured to receive an interleaved powercontrol signal on a different one of a plurality of power controlsubchannels, wherein each of the plurality of power control subchannelsis associated with a different mobile station in the mobile radiocommunication system.

[0096]FIG. 2F shows a base station 200 f that receives a plurality ofpower control signals formed from a plurality of mobile stations 100 fof the form shown in FIG. 1F, and uses the power control signals tocontrol the transmit power levels of first and second data streamstransmitted to the mobile stations. In the embodiment of FIG. 2F, thebase station 200 f is in the first active set and not the second activeset of the two mobile stations 100 f shown as being serviced by the basestation. Demodulation units 210, 214 and demutiplexers 221, 225 functionsubstantially as discussed above in connection with FIG. 2E. However,power control bit stream 260 output by demultiplexer 221 isrepresentative of the stream of power control commands 170 a transmittedto base station 200 e from a first mobile station of the form 100 f (asshown in FIG. 1F). The power control bit stream 260 is used to controlthe gain (or transmit power level) of transmitter 240, which transmitsthe first data stream 122 back to the first mobile station (MS1).Similarly, power control bit stream 262 output by demultiplexer 225 isrepresentative of a further stream of power control commands 172 atransmitted to base station 200 e from a second mobile station of theform 100 f (as shown in FIG. 1F). The power control bit stream 262 isused to control the gain (or transmit power level) of transmitter 242,which transmits a first data stream back to a further mobile station(MSx).

[0097] Although power control signals from two mobile stations 100 f areshown as being received by base stations 200 e,200 f it will beunderstood by those skilled in the art that base stations 200 e, 200 fcould be configured to receive power control signals from more than (orless than) two different mobile stations.

[0098]FIG. 2G shows a base station 200 g that receives a plurality ofpower control signals formed from a plurality of mobile stations 200 gof the form shown in FIG. 1G, and uses the power control signals tocontrol the transmit power levels of first and second data streamstransmitted to the mobile stations. In the embodiment of FIG. 2G, thebase station 200 g is in both active sets of the two mobile stations 100g shown as being serviced by the base station. Demodulation units 210,214 and demutiplexers 221, 225 function substantially as discussed abovein connection with FIG. 2E. However, power control bit stream 270 outputby demultiplexer 221 is representative of the stream of power controlcommands 180 a transmitted to base station 200 g from a first mobilestation of the form 100 g (as shown in FIG. 1G). The power control bitstream 270 is used to control the gain (or transmit power level) oftransmitters 240, 242 which transmits the first and second data streamsback to the first mobile station (MS1). Similarly, power control bitstream 272 output by demultiplexer 225 is representative of a furtherstream of power control commands 180 a transmitted to base station 200 gfrom a second mobile station of the form 100 g (as shown in FIG. 1G).The power control bit stream 272 is used to control the gain (ortransmit power level) of transmitters 248, 249, which transmit first andsecond data streams back to a further mobile station (MSx).

[0099]FIG. 2H shows a base station 200 h that receives a plurality ofpower control signals formed from a plurality of mobile stations 100 gof the form shown in FIG. 1G, and uses the power control signals tocontrol the transmit power levels of first data streams transmitted tothe mobile stations. In the embodiment of FIG. 2H, the base station 200h is in the first active set and not the second active set of the twomobile stations 100 g shown as being serviced by the base station.Demodulation units 210, 214 and demutiplexers 221, 225 functionsubstantially as discussed above in connection with FIG. 2E. However,power control bit stream 280 output by demultiplexer 221 isrepresentative of the stream of power control commands 182 a transmittedto base station 200 h from a first mobile station of the form 100 g (asshown in FIG. 1G). The power control bit stream 280 is used to controlthe gain (or transmit power level) of transmitter 240, which transmitsthe first data stream back to the first mobile station (MS1). Similarly,power control bit stream 282 output by demultiplexer 225 isrepresentative of a further stream of power control commands 182 atransmitted to base station 200 h from a second mobile station of theform 100 g (as shown in FIG. 1G). The power control bit stream 282 isused to control the gain (or transmit power level) of transmitter 248,which transmits a first data stream back to a further mobile station(MSx).

[0100] Although power control signals from two mobile stations 100 g areshown as being received by base stations 200 g,200 h, it will beunderstood by those skilled in the art that base stations 200 g, 200 hcould be configured to receive power control signals from more than (orless than) two different mobile stations.

[0101]FIG. 2I shows a base station 200 i that receives coarse and finepower control signals formed from a plurality of mobile stations 100 hof the form shown in FIG. 1H, and uses the power control signals tocontrol the transmit power levels of first and second data streamstransmitted to the mobile stations. In the embodiment of FIG. 2I, thebase station 200I is in both active sets of the two mobile stationsshown as being serviced by the base station. Demodulation units 210, 214and demutiplexers 221, 225 function substantially as discussed above inconnection with FIG. 2E. However, coarse power control bit stream 290output by demultiplexer 221 is representative of the stream of coarsepower control commands 184 a transmitted to base station 200 i from afirst mobile station of the form 100 h (as shown in FIG. 1H), and finepower control bit stream 292 output by demultiplexer 221 isrepresentative of the stream of fine power control commands 186 atransmitted to base station 200 i from a first mobile station of theform 100 h (as shown in FIG. 1H). The coarse and fine power control bitstreams 290, 292 are used to control the gain (or transmit power level)of transmitters 240, 242 which transmit the first and second datastreams back to the first mobile station (MS1). Similarly, coarse powercontrol bit stream 291 output by demultiplexer 225 is representative ofa further stream of coarse power control commands 184 a transmitted tobase station 200 i from a second mobile station of the form 100 h (asshown in FIG. 1H), and fine power control bit stream 293 output bydemultiplexer 221 is representative of a further stream of fine powercontrol commands 186 a transmitted to base station 200 i from a secondmobile station of the form 100 h (as shown in FIG. 1H). The coarse andfine power control bit streams 291, 293 are used to control the gain (ortransmit power level) of transmitters 248, 249 which transmit first andsecond data streams back to a further mobile station (MSx).

[0102]FIG. 2J shows a base station 200 j that receives coarse powercontrol signals formed from a plurality of mobile stations 100 h of theform shown in FIG. 1H, and uses the power control signals to control thetransmit power levels of first data streams transmitted to the mobilestations. In the embodiment of FIG. 2H, the base station 200 j is in thefirst active set and not the second active set of the two mobilestations shown as being serviced by the base station. Demodulation units210, 214 and demutiplexers 221, 225 function substantially as discussedabove in connection with FIG. 2E. However, coarse power control bitstream 294 output by demultiplexer 221 is representative of the streamof coarse power control commands 184 a transmitted to base station 200 jfrom a first mobile station of the form 100 h (as shown in FIG. 1H),Only the coarse (and not the fine) power control bit stream 294 is usedto control the gain (or transmit power level) of transmitter 240, whichtransmits the first data stream back to the first mobile station (MS1).Similarly, coarse power control bit stream 295 output by demultiplexer225 is representative of a further stream of coarse power controlcommands 184 a transmitted to base station 200 j from a second mobilestation of the form 100 h (as shown in FIG. 1H). Only the coarse (andnot the fine) power control bit stream 295 is used to control the gain(or transmit power level) of transmitter 248, which transmit a firstdata stream back to a further mobile station (MSx).

[0103] Although power control signals from two mobile stations 100 h areshown as being received by base stations 200 i, 200 j, it will beunderstood by those skilled in the art that base stations 200 i, 200 jcould be configured to receive power control signals from more than (orless than) two different mobile stations.

[0104]FIG. 2K shows a base station 200 k that receives coarse and finepower control signals formed from a plurality of mobile stations 100 iof the form shown in FIG. 1I, and uses the power control signals tocontrol the transmit power levels of first and second data streamstransmitted to the mobile stations. In the embodiment of FIG. 2K, thebase station 200 k is in both active sets of the two mobile stationsshown as being serviced by the base station. Demodulation units 210, 214and demutiplexers 221, 225 function substantially as discussed above inconnection with FIG. 2E. However, coarse power control bit stream 296output by demultiplexer 221 is representative of the stream of coarsepower control commands 188 a transmitted to base station 200 k from afirst mobile station of the form 100 i (as shown in FIG. 1I), and finepower control bit stream 298 output by demultiplexer 221 isrepresentative of the stream of fine power control commands 188 btransmitted to base station 200 k from a first mobile station of theform 100 i (as shown in FIG. 1H). Only the coarse power control bitstream 296 is used to control the gain (or transmit power level) oftransmitter 240, which transmits the first data stream back to the firstmobile station (MS1). The coarse and fine power control bit streams 296,298 are used in combination to control the gain (or transmit powerlevel) of transmitter 242, which transmits the second data stream backto the first mobile station (MS1). Coarse power control bit stream 297output by demultiplexer 225 is representative of the stream of coarsepower control commands 188 a transmitted to base station 200 k from afurther mobile station of the form 100 i (as shown in FIG. 1I), and finepower control bit stream 299 output by demultiplexer 225 isrepresentative of the stream of fine power control commands 188 btransmitted to base station 200 k from a further mobile station of theform 100 i (as shown in FIG. 1H). Only the coarse power control bitstream 297 is used to control the gain (or transmit power level) oftransmitter 248, which transmits a first data stream back to the furthermobile station (MSx). The coarse and fine power control bit streams 297,299 are used in combination to control the gain (or transmit powerlevel) of transmitter 249, which transmits a second data stream back tothe further mobile station (MSx).

[0105]FIG. 2L shows a base station 200 l that receives coarse powercontrol signals formed from a plurality of mobile stations 200 i of theform shown in FIG. 1I, and uses the power control signals to control thetransmit power levels of first data streams transmitted to the mobilestations. In the embodiment of FIG. 2L, the base station 200 l is in thesecond active set and not the first active set of the two mobilestations shown as being serviced by the base station. Demodulation units210, 214 and demutiplexers 221, 225 function substantially as discussedabove in connection with FIG. 2E. However, coarse power control bitstream 300 output by demultiplexer 221 is representative of the streamof coarse power control commands 188 a transmitted to base station 200 lfrom a first mobile station of the form 100 i (as shown in FIG. 1I).Only the coarse power control bit stream 300 is used to control the gain(or transmit power level) of transmitter 242, which transmits the seconddata stream back to the first mobile station (MS1). Coarse power controlbit stream 301 output by demultiplexer 225 is representative of thestream of coarse power control commands 188 a transmitted to basestation 200 l from a further mobile station of the form 100 i (as shownin FIG. 1I). Only the coarse power control bit stream 301 is used tocontrol the gain (or transmit power level) of transmitter 249, whichtransmits a second data stream back to the further mobile station (MSx).

[0106] Although power control signals from two mobile stations 100 i areshown as being received by base stations 200 k, 200 l, it will beunderstood by those skilled in the art that base stations 200 k, 200 lcould be configured to receive power control signals from more than (orless than) two different mobile stations.

[0107] Transmission of the interleaved power control signals 110 from amobile station to base stations operating in accordance with the presentinvention can be performed by way of a power control channel or a powercontrol subchannel as described above. Each interleaved power controlsignal 110 transmitted to a base station by way of a power controlsubchannel can, for example, be a conventional 800 bits per secondclosed loop power control signal. The interleaving performed by units146, 148 can be performed by a puncturing method well understood bythose skill in the art. In one example, an interleaved power controlsignal 110 is formed using mobile station 100 (FIG. 1A) by interleavingtwo bits of power control information for each of signals 120, 122 and124 with four bits of power control information for each of signals 120a, 122 a and 124 a. This is followed by another two bits of powercontrol information for each of signals 120, 122 and 124 and anotherfour bits of power control information for each of signals 120 a, 122 aand 124 a, and so on. By varying the number of power control bitsallocated to each signal during the interleaving process, the bit ratewithin interleaved signal 110 of the power control bit streamscorresponding to the signals 120, 122, 124 can be made smaller than thatof the power control bit streams corresponding to signals 120 a, 122 a,124 a. The bit rates of the power control bit streams included in theinterleaved signal 110 can also be shifted dynamically based on fadingconditions.

[0108] The previous description of the preferred embodiments is providedto enable a person skilled in the art to make and use the presentinvention. The various modifications to these embodiments will bereadily apparent to those skilled in the art, and the generic principlesdefined herein can be applied to other embodiments without the use ofthe inventive faculty. Thus, the present invention is not intended to belimited to the embodiments shown herein but is to be accorded the widestscope consistent with the principles and novel features disclosed.

What is claimed is:
 1. In a communication system, a method comprising:determining a first stream of power control commands; determining asecond stream of power control commands; interleaving the first andsecond streams of power control commands; transmitting the interleavedstreams of power control commands to a first and second base stationsfor controlling transmit power levels of a plurality of different datastreams.
 2. The method as recited in claim 1 further comprising:receiving, at a mobile station, a first data stream from the first basestation and from the second base station, and receiving a second datastream from the second base station at the mobile station, wherein saidfirst and second data stream are included in said plurality of differentdata streams.
 3. The method as recited in claim 1 further comprising:receiving the interleaved streams of power control commands at the firstand second base stations; de-interleaving the received interleavedstreams of power control commands for forming, at the first and secondbase stations, respectively, the first and second received streams ofpower control commands.
 4. The method as recited in claim 1 furthercomprising: controlling transmit power level of data transmitted fromthe first base station in accordance with the first stream of powercontrol commands, and controlling transmit power level of datatransmitted from the second base station in accordance with the secondstream of power control commands.
 5. The method as recited in claim 4wherein at least a portion of the data stream transmitted from the firstbase station at a power level in accordance with the first stream ofpower control commands and at least a portion of the data streamtransmitted from the second base station at a power level in accordancewith the second stream of power control commands are the same datatargeted for a mobile station.
 6. The method of claim 1, wherein thefirst stream of power control commands has a first bit rate within aninterleaved power control signal and the second stream of power controlcommands has a second bit rate within the interleaved power controlsignal.